The vehicular mode of ground transportation along roadways such as private automobiles, buses, trucks and the like plays a basic role in the societies and economies of all industrialized countries. The easy mobility that the private automobile offers has made it an indispensable tool of modern civilization. Enormous sums of money have been spent to transform early dirt roads into smooth concrete streets and vast super-highway systems. A large sum of money has also been spent for mechanical improvements of the motor vehicle. Although important improvements have been made, such as the self-starter and automatic transmission, the basic manual operation involving steering, accelerating and braking has remained essentially unchanged, since the invention of the automobile itself. On the other hand, the airplane, which was invented after the automobile and which requires a much more complicated control system, improved much more rapidly. For example, the automatic pilot was invented only about twenty-five years after the airplane itself, yet it provided essentially automatic flight control. It has been almost one hundred years since the automobile was invented and there is still no viable automatic guidance system available. The present invention is intended to not only provide an automatic guidance system similar to the automatic pilot, but to extend it well beyond this system to provide an essentially complete automatic driving system.
Specifically, the present invention will provide an economical and safe, all-weather, automatic guidance system for essentially all types of road vehicles that includes: automatic steering, automatic speed and headway control, automatic roadway identification and position determination, automatic lane changing and branching onto connecting roadways, automatic route following and automatic route selection. Although at first glance, this concept may be dismissed as "science-fiction", we shall disclose herein that such a system is within easy reach of being realizable with present state-of-the-art technology.
The prior art does contain concept proposals for vehicular automatic guidance but all these systems are very limiting in that they provide for only automatic steering control. In particular, these prior-art designs are based on having the vehicle follow an electric cable that is embedded in the middle of the roadway and fed with an electric current. In theory, the vehicle is guided over the cable by a closed loop control of the steering mechanism which senses the magnetic field generated by the current in the cable and thereby keeps the vehicle moving directly over it. Unfortunately, the system requires the expenditure of large amounts of electrical energy and a system to provide this electric current. Hence, in addition to being a large consumer of electrical energy, this system is also vulnerable to instantaneous and complete failure which would result from a single short circuit. This potential for failure would increase during bad weather conditions when the result of such failure would be most hazardous. Furthermore, no provision is made for automatic speed or headway control or for automatic lane changing or branching and the prior art appears completely devoide of these important considerations. Finally, the large scale installation of the current carrying cables would be very costly. For a detailed description of this prior art system see "An Automatic Guidance System for Road Vehicles,"IEE International Conference on Automobile Electronics, 6-9 July, pp. 140-143 by R. Bosch, and U.S. Pat. No. 3,482,644 entitled "Steering Control System For Unmanned Vehicles," by H. B. Krieger and K. A. Wilson.
The prior-art also contains an automatically guided material mover for operation inside office buildings or on the floors of large manufacturing plants. This automated vehicle moves along a selected path by following an invisible ultraviolet fluorescent strip that has been "painted" directly onto the floor's surface. The ultraviolet fluorescent path is visible only under "black light." The vehicle is equipped with an ultraviolet lamp that is mounted under it which stimulates the guide strip to fluoresce and emit visible light. Photoelectric sensors that are also mounted under the vehicle, pick up the stimulated fluorescent path. These sensors, along with electrical control circuity, automatically guide the vehicle along the path by a steering motor. The operating details of this vehicle are disclosed in U.S. Pat. No. 3,935,922 entitled "Vehicle Guidance Mechanism." Although this system does use a non-powered, passive guidestrip, it is even more vulnerable to failure during out-door operations than the former system using the electrified cables. For example, accumulated dirt or litter that are unavoidable on outdoor roadways, would cut off the vehicle's ultraviolet radiation and thus render the vehicle's photoelectric sensors completely useless. In addition, the painted fluorescent guidestrip would be subject to constant errosion due to weathering. Thus, in this system all of the roadways would have to be constantly cleaned and freshly painted--which would be impractical.
The automatic guidance system introduced herein is based upon utilizing a passive, low-cost, metallic guiderail embedded longitudinally along the centers of ordinary concrete roadways that is immune to all weather conditions, is unaffected by dirt, litter or water, requires no expenditure of energy and which is essentially maintenance-free. A proximity transducer or metal detector is installed under the vehicle that senses the metallic guiderail and sends steering commands to the vehicle's steering actuators to keep it moving along a path directly over the guiderail. The rail sections do not have to be attached to each other and they could be easily laid into pre-cut grooves or slots by high speed, automated methods that could approach the speed and simplicity inherent in the painting of lane dividers. The disturbance to the roadway surface would be minimal and essentially invisible. Thus, ordinary vehicles without the guidance system could be driven over guiderail equipped roadways or non-guiderail equipped roadways without any noticeable change whatsoever. The economics are such that all existing streets and highways of large and small cities can eventually be equipped with the guiderails at relatively little cost. The total installation cost, for example, would be comparable to that expended for electric street lighting. The cost could be more than offset by the fuel savings resulting from a more efficient traffic flow and the savings arising from fewer accidents. By adding a relatively inexpensive system of transponders that are also embedded in the roadway at various points along the guiderail and wiring them to a central traffic control computer, the system is expanded to provide not only automatic steering but automatic speed and headway control, automatic position determination, automatic route selection and optimal traffic flow.